I have the XD600 set to 4 channel mode, so it's summing the inputs for Channels 5 and 6. The questions I still have on my mind are:

1) Since I am using the Flatline crossovers, do I still need to set Ch 1 & 2 to high pass and Ch 5 & 6 to low pass? Or should I leave the filter mode to 'off' on the XD600? Ch 3 & 4 is set to high pass since it's powering the OEM rears.
2) If I should still use the lowpass/highpass switches on the amp itself, what are the recommended crossover frequencies for the Flatlines?
3) What gain settings are recommended for the Flatline midrange/tweeter and the underseats when hooked up to an XD600/6?

Here's where I am having some slight issues.

I have the gain for Ch 1 & 2 set to the minimum level, as setting it to anything higher and I seem to get some 'white noise' coming through the fronts. It's not obvious when music is playing, but when the music fades away or when I have soft music playing, I can faintly hear it. This noise was actually also present with the OEM Hifi system, so I'm not too bothered by it. I'm just wondering if others are experiencing the same thing.

Another issue I might be having is that I don't seem to be getting much bass. The mids and highs sound incredible, so far. But the lows seem a little weak. I have no basis for reference, so maybe it's doing what it's supposed to be doing. But at the moment, I don't notice much of an improvement in the lows from the OEM Hifi system (Do note I was never seeking after or expecting 'window-rattling' bass). I don't think I connected the polarity of the woofers wrongly. For Ch 5 & 6, I have the gain set to just very slightly above minimum, probably about 1/8th of a turn. I'm afraid to turn it up higher as my driver's underseat seems to be making some rattling noises on even moderately bassy tracks at moderate volumes, like as if it's being stressed too much.

Oh, I should mention also that I laid out new wiring through the car, from the amp to each of the speakers. I actually fed two sets of 16ga wire through the doors, which wasn't a completely easy task, but also wasn't as hard as I thought it was going to be!

2nd try
This was with
Morel Dotech and Jehnerts with OEM rears this should get you close except for
the doors. No gain at all on the rear speakers and still you have to fade them out.
Door Crossovers were set to -3db

Hi ctuna, thanks very much for the help! I will post some photos of my setup and wiring once everything is settled, hopefully that will be my small contribution back to the community!

I figured out what was making the rattling noises on my driver's underseat. There was a little piece of broken plastic (like a small piece of a ziptie) bouncing about on the cone, causing rattling noises even at low gains at low volumes. I removed the debris and turned up the gains and the lows are sounding incredible!

One question though, on your photo, for Ch 5 & 6, it looks like you've got the gain for the underseats turned up to the max. Is this correct? I can't really get past 6 o'clock (about halfway through full travel) without everything sounding too boomy.

Also, the final issue I seem to be having is the hiss/white noise coming through the midrange and especially the tweeter. It's faint when the gain for Ch 1 & 2 is set to min at 1 o'clock, but when I turn it up even a little, say to 2 or 3 o'clock, it gets somewhat noticeable when music fades in or out or when I'm listening to pure vocals. I have plugged out my rca inputs into the amp and the hiss vanishes. My input wiring is set up as follows:

Jehnerts are a 11 o clock not even half way .
The Morels are turned up just a little from all the way off.
Morels play lower so you may have to account of that with
your frequency adjustments.
Is your source music recorded at a high enough level to be above the noise floor.
Never had noise on either the stock OEM system or the aftermarket system . Any thing will sound noisy if the volume is floored I think . It shouldn't happen at moderate levels.

You should be getting incredible accurate tight
3d bass from this setup I do. And actually the bass
takes off before the door speakers do in my case.
I can occasionally feel the bass through the seats,
but its not getto bass that just rattles the car.

My kit came with 04 power cable and is grounded at the battery (on the battery I was told this the least noisy ground in the car)

Yes, the bass is incredible. It's tight and controlled, yet I still feel the punch. I have the gain set to 6 o'clock for the underseats, and it seems to be sufficient at the moment. If I go any higher, the lows seem to become a bit too 'boomy', if that's the right word to describe it, and overpowers the mids/tweeters.

I can't figure out the hiss yet. It seems like a soft 'electronic whine' of sorts. I don't think it's related to the alternator, as it doesn't correlate with rpm. It's more like background hiss/static. I can't turn up the gains on the doors above minimum, or the hiss becomes pretty apparent.

My rca extensions from the harness to the amp are just 'regular' unshielded/untwisted cables, so I'm not sure if those could be picking up noise. Also, the new wiring from the amp to the speakers runs either along the left side of the car for the lefts, or along the transmission tunnel and up above the glovebox for the rights.

I will try grounding at the battery but i need to get a longer ground wire first. I'm currently grounding at the left fender above the amp. Any other things I could look at?

The Hi Fi harness from Technic is pretty foolproof
It doesn't leave much for you to mess up if its like the ones
that came with mine.

The crossover that came with the Jehnerts just goes between the
tweeters in the doors and the doors is this correct?

Some people have pulled out the Inputs at the amp to see if noise still
persists. If it doesn't it suggests the noise is coming from the head unit.
This would mean the Head Unit is not grounded with respect to the
Amp or defective .

Thanks for the link! I read through some of the posts and it seems my symptoms are pretty similar. I've attached a photo of my amp mounting and wiring.

The amp/crossover unit is mounted on two custom milled aluminum panels. The lower panel is where the Jehnert crossovers are mounted, and the upper panel is where the XD600/6 is mounted. The upper panel has access holes to plug cables into the crossovers below. The entire assembly is mounted onto the OEM amp bracket (which had its two angled metal arms on the inboard side cut off). The custom milled panels have access holes on them to allow securing the OEM bracket to the factory mounting points. The two decks are separated using nylon spacers, and between the spacers and panels, rubber washers are used to provide shock/vibration dampening.

My symptoms are basically:
- Hiss/static from midrange/tweeter on both left and right doors
- Hiss is proportional to gain setting
- Disappears when I unplug RCA inputs from the amp
- Hiss was there when OEM amp/speakers were being used, but just much less noticeable (actually a lot less!)

In the photo, you can see where the RCAs from Technic's harness is connected to the male-male RCA extensions. The red live wire is temporarily crossing over the trunk to the battery, as I haven't yet finalized its routing. Any clues perhaps?

One other thing... I noticed earlier the amp itself was making some sort of electrical humming noise. When I wiggled the power and ground cables near to where they insert into the amp, the humming stopped. Anyone know what this is about?

- Hooked up mp3 player to amp. No hiss at all. Blissful silence. I want to believe that this means the amp and the new wiring to the speakers is not the culprit.
- Removed the male-male rca extensions and swapped out the female rcas on the harness for male ones. Plugged harness directly into amp and the hiss returns.
- Grounded amp at battery ground post on right bumper, no difference and hiss is still there.

The hiss is noticeable on front doors, but is particularly noticeable on the rears.

I think you are going to have to ask one of higher gods here
Like Technic or VP .
I saw some stuff about putting in ground loop isolators before but you
shouldn't really have to do that.
What about measuring the ground between the radio and amp?
You have better tweeters now that are more highly sensitive to high
frequency's therefore more noise.
Also my ground goes right to the battery tightening bolt on the battery clamp
that grabs the battery post .

Ive run into issues like this in the past, almost 100% solved by grounding the headunit and amp in the same locations. Im not 100% familiar with BMW electronics but this will prevent the audio cables from trying to balance the current.

You swapped a 180W max OEM amp with a 600W aftermarket amp. Original OEM hiss will increase proportionally.

A DSP processor could solve this problem by digitizing the OEM signal and thus removing the OEM noise/hiss floor before the aftermarket amp, everything else being equal.

Quote:

Originally Posted by MJ777LR

Thanks for the link! I read through some of the posts and it seems my symptoms are pretty similar. I've attached a photo of my amp mounting and wiring.

The amp/crossover unit is mounted on two custom milled aluminum panels. The lower panel is where the Jehnert crossovers are mounted, and the upper panel is where the XD600/6 is mounted. The upper panel has access holes to plug cables into the crossovers below. The entire assembly is mounted onto the OEM amp bracket (which had its two angled metal arms on the inboard side cut off). The custom milled panels have access holes on them to allow securing the OEM bracket to the factory mounting points. The two decks are separated using nylon spacers, and between the spacers and panels, rubber washers are used to provide shock/vibration dampening.

My symptoms are basically:
- Hiss/static from midrange/tweeter on both left and right doors
- Hiss is proportional to gain setting
- Disappears when I unplug RCA inputs from the amp- Hiss was there when OEM amp/speakers were being used, but just much less noticeable (actually a lot less!)

In the photo, you can see where the RCAs from Technic's harness is connected to the male-male RCA extensions. The red live wire is temporarily crossing over the trunk to the battery, as I haven't yet finalized its routing. Any clues perhaps?

One other thing... I noticed earlier the amp itself was making some sort of electrical humming noise. When I wiggled the power and ground cables near to where they insert into the amp, the humming stopped. Anyone know what this is about?

Thanks for the input and help everyone... The problem may still be there but your suggestions have been invaluable in troubleshooting. I read in another thread where someone also had similar issues, with the hiss being very slight with the OEM system, and then putting in an aftermarket amp made the hiss much more noticeable (makes sense, the signal from the headunit is being 'amplified'). In you guys' experience then, could this be a bad headunit or bad grounding of the headunit?

If the headunit itself is good (assuming), would a new carefully routed twisted pair RCA line from the headunit to the amp improve the situation?

Technic, you mean like an MS-8 between the HU and the XD600? That would be on my wish list, but I might have to wait a while before spending more on car audio!

On a very side/off-topic note, I finally put on a set of performance blackout grilles. I can't believe I waited that long to get a set. They look stunning on sparkling graphite! That was the silver lining to the day, with all the noise issues going on.

What could cause a high resistance ground to the radio?
The first thing I would do is reseat the connector to the radio
as sometimes connection points can oxidize over time and get
resistive. I wonder if there is physical ground in the factory
harness that runs from the radio to the amp? Check that if it exists.
I imagine the next thing would be to run another ground wire to the
amp from the radio as suggested to get a physically known ground
to it.

By the way it was Technic that responded in the last reply not VP,
Thanks Technic.
If you get flustrated take a break.

Oops, sorry to Technic and VP about the mixup, I've corrected my post above. I guess it's been a long day!

Sorry if this is obvious ctuna, but did you mean measure the resistance between one of the ground terminals on the rca input jacks and the ground terminal of the amp (where you insert the ground cable)?

By the way Technic, I know your amp harness is not the cause of the noise. Many have used it without issue. Plus like I said, the noise was there in the OEM setup, just much less noticeable. I hope I didn't come across as implying that when I said that anything post-amp couldn't be the cause of the noise. I think at worse case, I might run a new pair of RCA wires from the HU to the amp. If I remember right, I saw somewhere that you made a harness for that connects to the back of the HU. I might contact you at some point to get one.

I meant the actual ground connector that comes out of the radio
as in the power connector. Like the power connector for the amp,
which has +12 and ground.

The ground connector and wire from the back of the radio
would be the point of interest for me . I would measure from
that pin to the amp . This is theoretical but I used to work in electronics
and connectors are the enemy of a good connection usually . Connectors
can easily develop a several ohm resistance and some times just re seating
them will wipe the oxidation away and return things to normal. I do not
know how the ground is routed in the car or what it has to go through to reach
the trunk it could be in the harness or the chassis. So checking the ground
pin out of the back of the radio to the ground in the trunk seems like a good check point . Also laying in a new ground wire from the radio to the amp
might be a thing to do as the guy that mentioned tying the ground between
the radio and amp as suggested.

Oops, sorry to Technic and VP about the mixup, I've corrected my post above. I guess it's been a long day!

Sorry if this is obvious ctuna, but did you mean measure the resistance between one of the ground terminals on the rca input jacks and the ground terminal of the amp (where you insert the ground cable)?

By the way Technic, I know your amp harness is not the cause of the noise. Many have used it without issue. Plus like I said, the noise was there in the OEM setup, just much less noticeable. I hope I didn't come across as implying that when I said that anything post-amp couldn't be the cause of the noise. I think at worse case, I might run a new pair of RCA wires from the HU to the amp. If I remember right, I saw somewhere that you made a harness for that connects to the back of the HU. I might contact you at some point to get one.

Ok, I think I might try that, running a new ground wire for the headunit. Just to clarify, the intent is to connect the headunit power ground to the same grounding post that the amp power ground is connected to, correct? So if I currently have my amp grounded at the top of the rear left fender, I should run a wire from the headunit to this same ground point on the rear left fender too?

Yup, I think I will try doing the reseat first and perhaps add a new ground wire, if that doesn't work. I've been searching to see what an appropriate gauge of wire would be for this. Some places suggest thinner wire while some suggest heavier gauge wire. Any tips on this? If I do run a new ground wire, should I disconnect the HU's factory ground wire?

By the way, is it normal for an alternator to make a whining noise when charging a battery that's close to drained? I'm asking because, there were a few times when I would run the car on acc for several hours while doing cleaning, etc. Starting up the car after all that time, I would hear a whining noise that I always assumed was the alternator working harder than usual to recharge the battery. This was when I had the OEM Hifi system. Since I thought it was 'normal' I never really bothered to check if the noise was coming physically from the alternator or whether it was coming from the speakers. Now I'm wondering if that was alternator whine all along...